The most common and well-known form of cathode ray tube includes an electron gun for providing a visual display on a substantial rectangular viewing portion of a cathode ray tube. The viewing portion of the cathode ray tube is usually substantially spherical-shaped with a convexo concave configuration. As a result, the visual display of the cathode ray tube directed onto a flat surface tends to have a significant amount of de-focusing at the corners of the display.
In order to utilize the common form of cathode ray tube in a projection TV system for example, it has been required that relatively complex and separate optical components and lens be employed in an effort to reduce or minimize such de-focusing problems. Although such techniques have been and still are employed in such apparatus, it has been found that losses in light output, difficulty of alignment of the system and complexity and costs of the added components and apparatus are factors which tend to deleteriously affect such apparatus.
Additionally, it is known that the viewing portion of a cathode ray tube may be covered by a substantially similar-shaped glass panel to provide implosion protection for a viewer. Moreover, the similarly-shaped viewing portion and glass panel are usually bonded together by an epoxy or polyester resin to provide the desired protective shield. However, the added shield member serves as added protection but does not contribute to the resultant focus capabilities of the structure.